Method of making jacketed rods and the like



E. .M. SIMS Nov. 12, 1940.

METHOD OF MAKING JACKETED RODS AND THE LIKE Filed Feb. 17, 19 38 fizz/672527": I 5171655. 517716 Patented Nov. 12, 1940 METHOD OF MAKING JACKETED RODS AND I THE LIKE Ernest M. Sims, Elkhart, Ind. Application February 17, 1928, Serial No. 190,925

2 Claims.

This invention relates to jacketed rods and the like and their manufacture. The nature of the invention may be readily understood by reference to one illustrative embodiment thereof shown in "5 the accompanying drawing.

In said drawing:

Fig. 1 is a diagrammatic view illustrating the method of making the product; p

Fig. 2 is a fragmentary. longitudinal section of the product on an enlarged scale, illustrating the action of the die; and

Fig. 3 is an enlarged cross-section of a finished jacketed rod.

Machine elements for many industrial uses must be corrosion resisting. For example, pump and other rods used in oil wells if made of steel last only a few weeks. Rods made of corrosion resisting metal, such as Monel metal, are, however, very expensive. Since Monel metal and similar metals have very desirable properties in this connection, I propose to provide rods and the like with a heavy jacket of Monel metal or the like.

The practical application of such a jacket pre- 5 sents substantial problems. Application of a jacket by plating is not regarded as commercially practicable, among other reasons, because a thick plating would be prohibitively expensive and would not be uniform or possess substantial strength. I have found that jacketed rods may be made commercially according to the process herein disclosed by employing a welded jacket tube of Monel metal or the equivalent made from strip material. By this method of formation, a 35 tube of adequate thickness and of uniform dimensions and wall thickness can be obtained. Uniformity of dimensions, and particularly uniformity of wall thickness, is practically essential to successful commercial manufacture.

According to the illustrative method, the jacket is formed sufficiently larger than the core II to permit it to be slipped over the latter without difficulty. It should be understood that the core ll may be in the form of a rod or thick walled tube. Its cross-sectional area, in either case, should be adequate to assume the stress imposed thereon. For pump rods in deep wells where the tensile stress is high, high tensile strength steel, such as S. A. E. 4615 steel, may advantageously be used for the core. After the jacket has been preliminarily assembled over the core, as aforesaid, the assembly is drawn through a die I2 which reduces the jacket, including its innerdiameter, to bring it into close contact with the 55 core. The reduction of the jacket is substantial enough to generate rather high temperatures in the jacket during the'reducing operation, with the result that the inner surface of the jacket is drawn into contact with the core while the former (but'not the latter) is-in heated condition. By this method it is possible to heat the jacket without substantially heating or expanding the core. The ensuing contraction of the'jacket on cooling substantially increases the intimacy of contact between it and the core. Indeed a microscopic investigation reveals that the jacket follows the minutest surface irregularities of the core and that the contact is as closeand intimate as though the jacket were a metal plating electrolytically applied. .Fig. 2 illustrates on an enlarged scale the reduction in wall thickness and internal diameter'to which the jacket is subjected in passing through die l2.

The resulting product may be employed in the same manner and will have the same life and resistance to corrosion as a rod made entirely of the jacket material. It is generally the practice to polish the exterior surface of the jacket; and a polished Monel jacketed rod has almost an indefinite life. The jacket, of course, very substan- .25 tially supplements the strength of the core, and in determining the strength of the combined rod and jacket, the assumption may be made that the jacket is integral with the core.

It is important for the success of the illustrative method that the jacket be uniform in its dimensions. A seamless drawn jacket is unsatisfactory since it is impossible to avoid variations, particularly in wall thickness and internal diameter. These variations are not objectionable in ordinary uses of seamless drawn tubing, but in the present process they interfere substantially with its successful practice.

' Tubing made fro-m strip material (which has practically constant thickness) shaped into tube 40 form and butt welded provides a jacket with which the aforesaid process may be successfully practiced. The details of the method of making the jacket tubing need not be described. It can be made by conventional forming dies which progressively bend a strip of sheet material into tubular form. The formed tube may then be passed through welding apparatus, such as a gas Welding apparatus, which butt welds the edges of the metal. If desired, the welded jacket tubing may be passed through a conventional swaging operation to 'obliterate the weld seam and size the jacket to proper diameter.

The jacket may advantageously be applied with the aid of the conventional draw bench 5 mechanism. For this purpose one end of the jacket tube is preliminarily reduced in diameter by swaging or otherwise to permit insertion through the die and engagement with the conventional jaws l3 of the draw bench. Preferably a plug M is inserted in the end of the tube for supporting the tube against the gripping pressure exerted thereon by the jaws. The core extends into the tube up to the entrance to the die l2. Thereupon the draw bench is set into operation and the jaws serve to draw the assembly through the die l2. The latter is, of course, anchored against the pull on the tube. The amount of reduction in wall thickness of the jacket and internal diameter of the latter depends somewhat on its original thickness and diameter. One illustrative jacketed rod will sufflee to illustrate the extent of this reduction. A

jacket having an outside diameter 1.29" and a wall thickness of .049" is employed to jacket a core having an external diameter of 1.160". The initial internal diameter of the jacket is 1.192. It is, therefore, .032" larger in internal diameter than the core. In the drawing operation, the wall thickness of the jacket is reduced about 5% to .047" and its internal diameter is, of course, reduced, as aforesaid, to secure a tight envelopment of the core. The reduction of the internal diameter of the jacket by .032 as well as the reduction in wall thickness of .002 is sufficient to develop a very substantial amount of heat whereby the jacket is fitted to the core while in heated condition with the aforesaid results.

Obviously the invention is not limited to the details of the illustrative embodiment herein i1- lustrated and described since these may be variously modified. Moreover it is not indispensable that all features of the invention be used conjointly since various features may be used to advantage in different combinations and sub-combinations.

Having described my invention, I claim:

1. The method of making a jacketed tension rod which is characterized by forming a tubular jacket from a strip of metal of uniform thickness, welding the strip to form a tube of uniform thickness, inserting a core rod in said jacket, the sectional area of the core being substantially greater than that of the jacket, reducing the diameter and thickness of said jacket to develop substantial heat in said jacket and while the same is in heated condition drawing the same down on to the core while maintaining said core relatively cool, and then cooling the jacket to cause it to shrink on the core.

2. The method of applying a metal jacket to a cylindrical core which is characterized by forming a tubular jacket from a strip of metal of uniform thickness, welding the strip to form a tube of uniform thickness, inserting a core of relatively large cross-sectional'area into the jacket, the sectional area of the core being substantially greater than that of the jacket, then reducing the internal diameter of the jacket only by drawing to develop substantial heat in the jacket while maintaining the core relatively cool by substantially limiting the reduction to the jacket, continuing the reducing operation until the jacket thus heated closely fits the relatively cool core, then allowing the jacket to cool to effect contraction thereof on the core.

ERNEST M. SIMS. 

